Moisture determination apparatus



March 3, 1970 SNELSQN 3,498,116

MOISTURE DETERMINATION l APPARATUS Filed OCt. 13, 1966 FIG. 2

. INVENTOR.

D.W. S N E LSON' ATTORNEYS United States Patent 3,498,116 MOISTUREDETERMINATION APPARATUS Dallas W. Snelson, Tulsa, Okla., assignor toPhillips Petroleum Company, a corporation of Delaware Filed Oct. 13,1966, Ser. No. 586,534 Int. Cl. G01n 5/02 US. CI. 7373 7 Claims ABSTRACTOF THE DISCLOSURE An apparatus for determining moisture content ofliquid petroleum gas. The apparatus includes a flow distributor, afilter, and a flow control means which is adjustable to a calibratedsetting.

This invention relates to the determination of the moisture content offluids. In one aspect this invention relates to an apparatus fordetermining the moisture content of a fluid. In another aspect, thisinvention relates to an apparatus for determining the moisture contentof a fluid, comprising adjustable snap acting means for changing from aflow restrictor in a flow passage to another position wherein the flowthrough the passage is unrestricted.

Knowledge of the mois ure content of various fluids often is animportant consideration. 'For example, condensed moisture may interferewith the flow of gas in a pipeline and, under certain conditions oftemperature and pressure, moisture may combine with a gaseoushydrocarbon to form gas hydrates. The solid product thus formed maycollect in sufficient quantities to reduce the flow or even to plugcompletely the pipeline in which the flow is occurring. Thespecifications under which liquefied petroleum gases are sold ofteninclude moisture content. My invention is suitable for determining themoisture content of liquefied petroleum gas (LPG) hydrocarbons withoutresorting to laboratory analysis. A method suitable for determining themoisture content of fluids such as disclosed by Alquist, 3,196,667(1965) can be employed. Since tests are conducted without resorting tolaboratory analysis, problems have been encountered in alterations inthe testing zone by friction wear upon the calibrating members and bymechanical rotation of one part of the member while the cooperating partremains stationary. Such variations in data as obtained by using fieldmethods occur due to minor variations which are present when machinedparts are produced to work in close tolerance.

According to my invention a moisture determination apparatus having ahousing with a passage therethrough and an inlet and an outlet isconnected to a fluid source, such as a liquefied petroluem gas line, bya connection nipple which is connected to the inlet end of the housing.Moisture determination apparatus is also provided with an adjustableflow control means which is operatively connected to the housing andadapted to enter into a second choke which is positioned downstream froma first choke, the two chokes serving to restrict the flow of fluidthrough the passage. The second choke restricts the flow through thepassage more severely when the adjustable flow control means ispositioned in an operating position. The adjustable flow control meansis moved into two relative positions within the second choke. To changethe relative positions one to the other, the choke means and theadjustable flow control means in one of the relative positionscooperates to form a very small flow passage and the second choke andthe adjustable flow control member in the other of the relativepositions cooperate to remove the flow control member from the path offlow of fluid through the second choke.

Further according to my invention a fluid distributor is 3,498,116Patented Mar. 3, 1970 positioned within the passage adjacent the inletwithin the housing to produce increased expansion of the fluid flowingthrough the moisture determination apparatus. The fluid distributorfurther provides a flow diversion of the fluid to provide equaldistribution of flow across and through a filter which is alsopositioned within the passage downstream of the fluid distributor. Thefilter is maintained in position adjacent a first choke means by aresilient means abutting the fluid distributor and the filter to preventfluid from bypassing the filter as it is forced through the passage.

Further according to my invention a locking means is carried by the stemof the flow control member. The locking means is contacted with ashoulder within the housing of the moisture tester apparatus to provideadjustable control for regulating the size of the annular passage formedby the second choke and one end of the stem.

Further according to my invention there is provided a moisturedetermination apparatus having a swivel ball joint incorporated withinthe flow control means thereby preventing circular movement of a snapacting cam actuator from altering the relative positions of the flowcontrol member with respect to the second choke.

It is an object of the invention to provide an apparatus for determiningthe moisture content of fluids.

Another object of the invention is to provide an apparatus suitable fordetermining fluid moisture content under conditions of field operationswhich produce reproducible accurate data as to moisture content.

Another object of the invention is to provide an apparatus fordetermining moisture content having an adjustable flow control member sothat the moisture determination apparatus can be adjusted for differentfluids and different calibrations.

Other aspects, objects and advantages of the invention will be apparentto one skilled in the art from a study of the written description, thedrawing and the claims.

In the drawing FIGURE 1 illustrates a combination of elements useful indetermining the moisture content of a fluid.

FIGURE 2 is a vertical cross-section of a moisture determinationapparatus according to the invention.

FIGURE 3 illustrates flow control member of the moisture determinationapparatus of FIGURE 2.

Referring now to the drawings where like elements are designated by likenumerals, and particularly to FIGURE 1, there is shown a source ofliquefied petroleum gas (LPG) 10 in fluid communication through fluidconduit 13 with valve 11, pressure regulator 12 and moisturedetermination apparatus 20 respectively. Moisture determinationapparatus 20 is provided with cam lever 58 which can be positioned tocause restriction of flow of LPG through moisture determinationapparatus 20 in one posiging. This time is a function of the moisturecontent ofthe LPG flowing through the moisture determination apparatus.Liquefied gases containing known quantities of moisture are tested usingmoisture determination apparatus 20 to deermine time required forshutting off the restriction at various moisture concentrations, Theseresults so obtained are then plotted to form a curve of freezing timeversus moisture content. Upon determining the time required to shut offthe flow of fluid through the.

moisture determination apparatus one can use the above curve of freezingtime versus moisture content to determine the moisture content of thefluid being tested.

As shown in FIGURE 2, a moisture determination apparatus 20 is providedwith an inlet 21, an outlet 22 and a flow passage 23 extending throughhousing 24 which comprises a plurality of sections, 28, 29, 32 and 34,subsequently described. Inlet 21 is provided with threads so that aconnection nipple 26 having mating threads on one end can be attached tohousing 24. Connection nipple 26 is provided with a connection nut 27 asshown and a passage in fluid communication with passage 23 of housing 24thus enabling moisture determina tion apparatus 20 to be operativelyconnected to a fluid conduit carrying the fluid to be tested.

Housing 24 comprises a plug 28 which is operatively connected to filterhousing 29 by mating threads 31 as shown. Filter housing 29 isoperatively connected to control housing 32 by threaded connections 33.Control housing 32 is then connected to spring housing 34 by threadedconnection 36. Spring housing 34 is provided with a coaxial bore 37which is positioned furthermost removed from inlet 21 of moisture tester20. When assembled, plug 28, filter housing 29, control housing 32, andspring housing 34 combine to form a continuous housing 24 for moisturedetermination apparatus 20.

The plug 28 has a distributor portion 38 disposed internally of thefilter housing 29. Extending axially through the plug 28 is a bore 28awhich forms part of the passage 23. The distributor portion 38 isprovided with four circumferentially spaced orifices 35, three of whichappear in FIGURE 2. The axes of the orifices 35 extend perpendicular tothe axes of bore 28a so that the flow of fluids through plug 28 isdiverted and distributed upon entering passage 23 defined by housing 29.Immediately downstream of the distributor portion 38 and disposedconcentrically in passage 23 is a filter 39. Filter 39 is positionedwithin filter housing 29 and adjacent a choke 41 by means of a resilientelement 42 which abuts fluid distributor 38 in filter 39. Resilientelement 42 serves to maintain filter 39 against choke 41 at all times,thereby preventing the fluid passing through passage 23 from bypassingthe filter 39 and thus contaminating downstream portions of moisturedetermination apparatus 20. Choke 41 is provided with four orifices 25(two appearing in FIGURE 2) of fixed dimensions. The orifices 25 areradially spaced in the passage 23 thereby providing means fordistributing the fluid immediately upstream of the flow control meanswhich includes a choke nipple 43 and a stem 44 slidably mounted in thehousing 24. Choke nipple 43 has formed therein an orifice 43a whichcooperates with an end portion 49 of stem 44 to eifect throttling offlow therethrough. The choke nipple 43 is positioned within the controlhousing 32 and serves as a housing for body 40, an integral part of astem 44. The choke nipple 43 and control housing 32 are maintained inassembled relation by pin 46. The choke nipple 43 is further providedwith an opening 47 which is in fluid communication with outlet 22.

The stem 44 comprises the control body 40, a threaded portion 54 and astraight portion 48. Body 40 slidably fits internally ofthe choke nipple43 and has end portion 49 in registry with the orifice 43a. End portion49 is configurated to provide a radially outwardly taper in thedirection of fluid flow. Orifice 43a is similarly tapered so that endportion 49 disposed therein defines an annular passage 51. O-ring 50mounted on body 40 maintains a fluid seal for passage 23. Lock nuts 56mounted on the threaded portion 54 of stem 44 provides the means foradjusting the flow area of annular passage '51. The lock nuts 56 aremaintained in abutting relation to the end of choke nipple 43 by acompression spring 52 concentrically mounted on straight portion 48.Flanking collars 53 maintain the spring and stem 44 in the properassembled relation. Thus ro ation of the lock. nuts 56 in one directionreduces the flow area in annular passage 51, andin the oppositedirection enlarges it. This particular feature permits the flow controlmeans to be adjusted precisely to the calibrated setting.

The spring 52 urges the stem 44 towards a first position wherein thetapered end 49 extends concentrically into the orifice 43a and therewithdefine the annular passage 51. The stem 44 is moved to a second positionby means of a lever 58 disposed externally of the housing 24. Thestraight portion 48 extends through an aperture 37 formed in housing 24presenting a projection 48a externally of the housing 24. The projection48a is pivotally attached to a lever 58 by pin 59. Lever 58 comprises ahandle 61, a recessed opening 62, and a cam surface 63. The lever 58 isdisposed in a transverse attitude relative the stem 44 and is movableabout pin 59 towards axial alignment with the stem 44. Cam surface 63reacts with the housing 24 thereby causing the stem 44 to be moved tothe right as viewed in FIGURE 2 to the second position. A flat portionof cam surface 63 maintains the assembly in the second position. In thesecond position, the flow area through orifice 43a is substantiallygreater than that provided with the assembly in the first position.

It has been found that in moving the lever 58 from the transverse to theaxially aligned attitudes relative the stem 44, the reaction of the camsurface 63 on housing 24 creates lateral stresses on a rigid stem.Therefore, a pivotal connection in the form of a swivel ball joint 57 isprovided. The ball joint 57 permits lateral movement of the straightportion 48 relative to the threaded portion 54 thereby eliminating thestresses.

In operation, moisture determination apparatus 20 is inserted in a flowline to be tested so that liquid enters flow determination apparatus 20through inlet 21. As the fluid flows through inlet 21 and through flowpassage 23 fluid distributor 38 serves to provide increased expansion ofthe fluid flowing through the flow smoother and thereby providing a flowdiversion of the fluid to provide equal -di-stributi0n of the flowacross filter 39. As the fluid passes through filter 39 it is restrictedby choke 41 thereby causing an increased pressure and cooling eflect onthe fluid flowing through choke 4.1. Flow control means comprisingtapered end portion 49 of stem 44 and orifice 43a further restricts theflow thus increasing the pressure and upon passing therethrough thefluid is allowed to expand thereby causing a sudden cooling of the fluidbefore it passes through outlet 22. With the assembly in the secondosition, the flow area of passage 51 is greatly increased resulting insubstantially less expansion and consequent cooling. Where it is desiredto make the desired moisture measurements cam lever 58 is positioned toadvance stem 44 within spring housing 34 thereby causing the tapered end49 of control body 40 to enter orifice 43a and form annular passage 51.This sudden closing off of the flow passage through orifice 43a reducesthe flow through choke 43 a predetermined amount. Upon the fluid passingthrough annular passage 51 the fluid is subjected to a sudden expansionand supercooling eifect thus causing the moisture within the liquid tofreeze and close off annular passage 51. After calibration curves havebeen run the time which it takes the moisture within the fluid passingthrough annular passage 51 to freeze and thereby cut off the flow offluid through annular passage 51 and the size of annular passage 51 canbe used to determine the amount of moisture present from curves drawn inthe calibration of moisture tester apparatus 20. Annular passage 51 canbe adjusted by adjusting lock nuts 56 on stem 48, thereby increasing thesize of annular passage 51 by adjusting lock nuts 56 in such a manner asto partially withdraw the tapered end 49 of control body 40 from orifice43a.

Also, in operation, maintenance of the control system is greatlysimplified by means of the detachable units, in other words, the filterbody, the control housing, and the spring housing. When necessary toinspect or adjust stem 44, spring housing 34 and control housing 32 canbe separated thereby enabling the withdrawal of stem 44 without completedisassembly of the moisture determination apparatus 20. Further, sincethere is no friction contact between tapered end 49 of control body 40and second orifice 43a, wear does not occur upon these elements thuschanging the size of the elements because of operation. Further, swivelball joint 57 of stem 44 prevents movement of cam lever 58 frominfluencing the position of tapered end 49 of control body 40 withrelation to orifice 43a. Due to swivel ball joint 57 external pressureapplied on cam lever 58 or the top portion of moisture determinationapparatus 20 does not change the flow rate through orifice 43a. Swivelball joint 57 allows the operator to rotate cam lever 58 within 360without affecting the flow rate, thus reducing burdensome manufacturingtolerances.

Reasonable variations and modification are possible within the scope ofthe foregoing disclosure, the drawings and the appended claims to theinvention, the essence of which is a moisture determination apparatuscomprising adjustable flow passages for calibration, tapered replaceablesections in the flow control member and housing in a test zone, and aplurality of restricted flow passages to smooth flow into the test zoneafter liquid passes through a filter element, and means provided toprevent friction wear incorporated in the fiow control member andhousmg.

That which is claimed is:

1. An apparatus for use in determining moisture content of liquidpetroleum gas comprising:

(a) a housing having an inlet, an outlet and a passagewayinterconnecting said inlet and outlet;

(b) flow control means disposed in said housing for throttling the flowof gas through said passageway thereby causing expansion and coolingthereof comprising:

(1) an orifice,

(2) a stem slidably mounted in said housing and having an end portion inregistry with said orifice, and

(3) means for moving said stem between a first and second position, saidend portion in said first position and in cooperation with said orificedefining a first calibrated flow area, and said end portion in saidsecond position and in combination with said orifice defining a secondcalibrated flow area, said second flow area being greater than saidfirst flow area; and

(c) a flow restrictor of fixed dimension disposed in said passageway andupstream of said flow control means whereby gas flowing through saidpassageway is expanded through said flow restrictor and said flowcontrol means.

2. The invention as recited in claim 1 wherein said end portion isconfigured to provide a continuous radially outwardly taper in thedirection of fluid flow, said end position in said second position beingremoved from said orifice, said orifice having a tapered configurationconforming to that of said end portion, and said end portion n saidfirst position being disposed in said orifice, said first fiow areadefined thereby having a tapered annular configuration.

3. The invention as recited in claim 1 wherein said adjustment meansincludes locking means threadedly mounted on said stem and beingrotatable in one direction to move said stem toward said first positionand rotatable in the opposite direction to move said stem toward saidsecond position.

4. The invention as recited in claim .1 wherein said stem extendsthrough said housing presenting a portion externally thereof, and saidmeans for moving said stem includes biasing means for urging said sterntoward said first position and a lever mounted on said external portionof said stem and actuable to move said stem against the force of saidbiasing means to said second position.

5. The invention as recited in claim 4 wherein said lever is pivotallyconnected to said external portion of said stem and is normally disposedtransverse said stern, and has a cam surface engageable with saidhousing, said lever being movable toward axial alignment with said stemabout said :pivot connection, said cam surface reacting with saidhousing thereby moving said stem to said second position.

6. The invention as recited in claim 5 wherein said stern internally ofsaid housing includes a pivot connection whereby lateral stressescreated by said lever in moving toward axial alignment with said stemare eliminated.

7. The invention as recited in claim 6 wherein said pivot connection isa swivel ball joint.

References Cited UNITED STATES PATENTS 3,196,667 7/1965 Alquist et al.73-61.1

RICHARD C. QUEISSER, Primary Examiner I. WHALEN, Assistant Examiner US.Cl. X.R. 7329

